What is an abyssal plain?

The Abyssal plain Is the flat bottom of the sea floor that lies at an abyssal depth (3,000 to 6,000 meters), generally adjacent to a continent. These underwater surfaces vary in depth only from 10 to 100 cm per kilometer of horizontal distance.

They are irregular in their contour, but generally extended along the continental margins, the largest plains are hundreds of kilometers wide and thousands of kilometers long.

Abyssal plain

In the North Atlantic, the Sohm plain has an area of ​​approximately 900,000 square kilometers (350,000 square miles). The plains are larger and more common in the Atlantic Ocean, less common in the Indian Ocean, and even rarer in the Pacific, where they occur mainly as the small flat flats of the marginal seas or as the narrow, elongated bottoms of The trenches.

Description of the abyssal plains

The abyssal plains are incredibly flat and are composed of sediments averaging over half a mile thick. It is believed that most of this sediment comes from erosion on the earth being washed in the ocean.

This sediment sits on an irregular oceanic crust of more than 10,000 feet deep, filling any void and creating a flat surface. In the extreme depths of the abyssal plains, the water pressure is huge, temperatures are close to freezing, and it is dark.

Even so, many organisms live on the abyssal plains. They usually eat what is known as marine snow, which consists of fragments of dead bodies and feces of organisms that live far above them and that slowly drift up to the surface of the abyssal plains.

The organisms that live in the abyssal plains have extremely slow metabolisms and can spend months without eating. The abyssal plains are the vast, flat, sediment-covered areas of the deep ocean floor. They are the flattest, featureless areas on planet Earth, and have a slope of less than one foot difference in elevation per thousand feet of distance.

The lack of features is due to a thick blanket of sediment covering most of the surface. These flat abyssal plains occur at depths of more than 6,500 feet (1,980 m) below sea level. They are underlying the oceanic crust, which is predominantly basaltic, a volcanic rock of fine and dark grain.

Typically, basalt is covered by sediment layers, many of which are deposited by deep oceanic turbidity currents (caused by increased sediment-filled water), or biological materials, such as tiny reservoirs of marine plants and animals, which They come from the upper levels of the ocean.

Components of the abyssal plain

Components of the abyssal plain sediment include windblown dust, volcanic ash, chemical precipitates and occasional fragments of meteorites. Abyssal plains are often filled with manganese nodules containing varying amounts of iron, nickel, cobalt and copper.

These potato-sized nodules are formed by direct precipitation of seawater minerals onto a rock fragment. At present, manganese nodule deposits are not extracted from the seabed, but may be harvested and used in the future.

Of the 15 billion tons of clay carried by the river, sand and gravel washed in the oceans every year, only a fraction of this amount reaches the abyssal plains. The amount of biological sediment that reaches the bottom is similarly small.

Therefore, the rate of sediment accumulation in the abyssal plains is very slow, and in many areas, less than an inch of sediment accumulates in thousands of years. Due to the slow rate of accumulation and the monotony of the topography, it was believed that the abyssal plains were a stable and immutable environment.

Some currents have damaged trans-oceanic communication cables placed in these plains. Although they are more common and widespread in the Atlantic and Indian Ocean basins than in the Pacific, the abyssal plains are found in all major ocean basins.

The abyssal plains do not support a great abundance of aquatic life, although some species survive in this relatively sterile environment. Deep-sea dredgers have collected specimens of unusual-looking fish, worms, and clam-like creatures from these depths.

Location of the abyssal plains

Approximately 40% of the Earth's ocean floor consists of abyssal plains, while the rest of the ocean floor topography consists of underwater hills, deep trenches, and mountain ranges.

The abyssal plains are found in most of the major ocean basins of our planet, but are more common in the Atlantic Ocean.

Formation and composition of the abyssal plains

The accumulation of sediments derived from the earth for long periods of time in the ocean floor gives rise to the flat surfaces characteristic of an abyssal plain. The accumulation of these deposits, which average 1 kilometer thick, softens the irregular topography of the ocean floor.

However, in some areas where sediments incompletely bury the underlying topography, outcrops of clusters of hills or volcanic hills may affect the regularity of these abyssal plains.

Sediments of mud, sand and gravel, as well as volcanic ash, dust blown by wind and chemical precipitates from the continental margins, enter the oceanic waters to form dense sediments laden with sediments deposited in the ocean floor by Currents driven by turbidity.

The layers of such sediments accumulate over elongated periods of time, creating these abyssal plains. In addition to inorganic matter, organic matter, including the microscopic remains of innumerable organisms, are also deposited as layers in these abyssal plains.

The plains are believed to be the upper surfaces of the sediment derived from the earth that accumulates in the abyssal depressions, thus softening a preexisting or irregularly irregular topography. The seismic profiles (cross sections) of the abyssal plains reveal accumulations of sediments with an average of one kilometer of thickness, deposited on the wavy topography.

The incomplete burial of the preexisting relief may result in the presence of isolated volcanic hills or clumps of hills rising abruptly from some abyssal plains. The continental margin sediment accumulates on the steep continental slopes, and the resulting underwater detachment of this coarse material creates dense, sediment-laden sediments called turbidity currents flowing down the slopes in obedience to gravity.

Part of the sediment of the turbidity currents sits on the bases of the continental slopes, creating continental slopes of lower gradient, but part of the coarse sediment reaches the abyssal depressions. The horizontal beds of sand and even gravel, are fractions of a centimeter to several meters of thickness, comprise of 2 to 90% of the sediment of the abyssal plain.

Many of these layers are of shallow water organisms, for example, the Foraminifera microscopic protozoan. A single layer can be progressively thinner from bottom to top; This classification reflects the origin of the bed as the reservoir of a single stream of turbidity.

Biology of the abyssal plains

Although initially thought to be desert habitats, scientists have recently discovered high microbial biodiversity in the abyssal plains. The oceanographic expeditions carried out by the Abyssinian Marine Life Diversity Census have discovered the existence of about 2,000 bacteria, 250 protozoa and 500 species of invertebrates in the abyssal plains of the Earth's oceans.

Abyssobrotula galatheae and Pseudoliparis amblystomopsis are the two deepest marine fish species recorded to date. While some of the species in the abyssal zone, such as protozoan foraminifera, are practically universal in their distribution, others are endemic to some abyssal plains or specific trenches, such as certain crustacean isopods.

However, due to the abysmal depths of the abyssal plains, the exploration of such habitats demands great offers of time, effort and budget, which leads to the generation of only a low volume of data on the abyssal ecosystems, at least for now .

Importance of abyssal plains

The abyssal plains of the world are areas of great ecological, commercial and strategic importance. As fish from the upper reaches of the ocean are rapidly depleted by overfishing, marine fisheries are expected to exploit deeper and deeper living marine fish which, because of their slow rotation and longer life cycles, may be threatened Even faster.

Abyssal plains could also be exploited in the future for legal or illegal purposes, such as the dumping of hazardous wastes such as radioactive waste, such as a cemetery for ships and oil platforms landed and for the location of debris and debris from coastal areas.

Abyssal plains could also be the future sites for extraction of minerals, oil and gas, making the deep bed of the ocean susceptible to environmental degradation already be affected in the earth and shallower waters.

References

  1. The Gale Encyclopedia of Science. (2014). Abyssal plain. 20-1-2017, Gale Group.
  2. Dunn, T. (2012). Abyssal Plain: Definition & Facts. 20-1-2017, from Study.com.
  3. Extreme Science. (2015). Abyssal Plain. 20-1-2017, from Extreme Science.
  4. JRank Science & Philosophy. (2012). Abyssal Plain. 20-1-2017, from Net Industries.
  5. Reference.com. (2015). What is an abyssal plain?. 20-1-2017, from IAC Publishing.
  6. The Editors of Encyclopædia Britannica. (1998). Abyssal plain. 20-1-2017, from Encyclopædia Britannica Web site.
  7. World Atlas. (2016). What Is An Abyssal Plain?. 20-1-2017, from WorldAtlas.com.

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